Various inspection devices (referred to as modality devices, hereinafter) used in image diagnosis are essential in the modern medicine, because those inspection devices can perform minimally invasive inspection of a human body. Advances in performance of the modality devices have allowed a quality image of high resolution to be obtained and accurate and precise inspection to be achieved in image diagnosis. For example, a computed tomography (CT) apparatus can obtain high-resolution three-dimensional information on a tissue inside an object, and a magnetic resonance imaging (MRI) apparatus can perform imaging in various ways depending on the modality device, such as an MR angiography (MRA) that images fresh blood containing no contrast medium by MRI. With advances in medical image digitalization, a hospital information system (HIS) that is an ordering system that processes a request from a doctor via an electronic network, a radiology information system (RIS) and a picture archiving and communication system (PACS) that accumulates images obtained by the modality device as electronic data have been developed.
Advances of the modality devices have enabled easy and detailed observation of the inside of a living body. An enormous amount of data can be obtained, and many modality devices obtain data in the form of volume data composed of a plurality of images. The amount of volume data is no less than thousands of images when a whole body is imaged, and it is burdensome to a doctor or the like who performs radiological interpretation of these data to make a diagnosis. Radiological interpretation is an important task for diagnosis of a disease or determination of a treatment plan. It is not easy to analyze the enormous amount of medical images to make an early decision, although there is a demand for early detection. In view of such circumstances, as inventions for supporting image diagnosis, there have been proposed a radiological interpretation report creating apparatus that identifies an abnormal anatomical site and determines the degree of malignancy of the site by using a segmentation technique or the like (see Patent Literature 1, for example) and an image analyzing apparatus (see Patent Literature 2, for example) that determines a positional correspondence between images obtained in two different inspections.
Radiological interpretation and diagnosis need to be accurate, and to make an accurate diagnosis, an abnormal site or a site to be treated in the obtained medical image needs to be precisely grasped. However, to read an anatomical site from a medical image requires technical expertise. In view of this, techniques of representing or constructing an anatomical position in a human body through a mathematical approach have been studied and provided.
The “anatomical position” refers to a characteristic local structure in a human body (referred to as a local structure, hereinafter) that is important for understanding a medical image and serves as a mark when the human body is anatomically mapped. For example, an anterior arch (node) of a first cervical vertebra (cervical vertebra I) of a head is a local structure, a bifurcation of trachea in a chest is also a local structure, and an upper pole of a right kidney or the like in an abdomen is also a local structure. The position of the local structure (anatomical position) is automatically detected from the medical image obtained by the modality device, such as the X-ray CT device or the MRI device, by common image analysis, pattern recognition technique or the like.
In radiological interpretation, the position of the anatomical site displayed in the medical image needs to be correctly recognized. However, to identify an anatomical site or the position thereof in the obtained image requires technical expertise including knowledge and experience. In some cases, an enormous amount of data containing hundreds or thousands of medical images, such as volume data, is obtained per person in one X-ray CT or MRI imaging, and creation of a radiological interpretation report is a significant burden in image diagnosis. If hundreds or thousands of images are obtained, it is troublesome to find a required image, or more specifically, to find which image includes a desired anatomical site, which image has been selected as a representative image (referred to as a key image, hereinafter) which includes a finding, or in which image a mark (referred to as an annotation, hereinafter) is imparted to a particular position of interest.
The obtained medical image is stored in the PACS or the like as electronic data. The medical image data stored in the storage device is associated with various kinds of information on an inspection or a patient. Anatomical site information included in the retained medical image data may be recorded in any of information concerning an inspection or a patient. However, such a task is manually performed by an inspection technician, a radiologist or the like. In addition, such recording may not be performed, and specific details cannot be recorded. Therefore, to check what anatomical site is included in the retained medical image data, it is necessary to display the medical image data on a medical image display apparatus or the like and visually check the medical image data.
In view of such circumstances, there is a demand for a medical image processing apparatus that helps checking a content of a medical image based on the position (anatomical position) of the local structure described above.